1. Field of the Invention
Example embodiments of the present invention relate to a pad conditioner for a chemical mechanical polishing (CMP) apparatus, and more particularly, to a pad conditioner that may improve performance of a polishing pad for a CMP polishing apparatus.
2. Description of the Related Art
The manufacture of a semiconductor wafer may involve a CMP process. The CMP process may cause a scratch and/or some other defect in the wafer. For example, the CMP process may involve polishing a wafer using a polishing pad. Stress and/or impact may be applied to surfaces of the wafer and/or the polishing pad during the CMP process.
In a conventional CMP process, a wafer may be polished with a polishing pad and slurry may be supplied to the wafer. The slurry, by-products of the polishing, and/or a variety of foreign substances may be deposited on the surface of the polishing pad. Such deposits may cause degradation in a polishing rate, for example. Accordingly, a pad conditioner may be implemented to reduce a degradation in polishing performance. By way of example only, the pad conditioner may include particles of diamond and/or artificial diamond.
FIG. 1 is a plan view of a conventional pad conditioner 10.
Referring to FIG. 1, the pad conditioner 10 may have a surface supporting a polishing particle layer 12. The polishing particle layer 12 may include polishing particles adhered to the pad conditioner 10. The polishing particles may be artificial diamond particles, for example. The polishing particle layer 12 may be a mixture of various types of artificial diamond particles, as shown in Table 1 below.
Sample 1 (%)Sample 2 (%)Erect Type15.118.9Recumbent Type37.534.0Partially-Crushed Type32.832.7Irregular Type11.811.2Two-Particle Type2.83.2Total100.0100.0
Scratches and/or other defects generated during the CMP process may be caused by various factors, such as particles contained in the slurry, foreign substances, material characteristics and/or surface state of the polishing pad, and/or the artificial diamond particles being crushed and/or becoming detached from the pad conditioner. For example, the artificial diamond particles that may be crushed and/or detached from the pad conditioner may become interposed between the surfaces of the wafer and the polishing pad, possibly causing scratches and/or defects in the wafer.
As compared to the recumbent, the partially-crushed and the two-particle types of artificial diamond particles, the erect and the irregular types of artificial diamond particles may provide superior conditioning performance. However, the partially-crushed and the irregular types of artificial diamond particles may be more susceptible to being crushed, and the two-particle type of artificial diamond particles may be more susceptible to becoming detached from the pad conditioner. As can be appreciated from Table 1, the types of particles that may provide inferior conditioning performance (e.g., the recumbent, the partially-crushed and the two-particle types) and/or possibly cause wafer defects (e.g., the partially-crushed, the irregular and the two-particle types) may constitute a substantial portion of the particles in the polishing particle layer 12.
Various attempts have been implemented to improve the pad conditioner and associated polishing characteristics. In one example, a pad conditioner may include a first polishing particle layer having relatively small diamond particles fixed thereto and a second polishing particle layer having relatively large diamond particles fixed thereto. The first and the second polishing particle layers may form concentric circles. In another example, a pad conditioner may include a stepped surface having an upper portion and a lower portion. The same-sized artificial diamond particles may be adhered to the upper and the lower portions.